1. Field of the Invention
The present invention relates to an absorbent article including a sanitary napkin and a disposable diaper, and more particularly, it relates to an absorbent article having leakage preventing walls at two sides thereof.
2. Description of the Related Art
Absorbent articles, such as a sanitary napkin and a disposable diaper, sometimes have leakage preventing walls which extend in the longitudinal direction and are arranged in the width direction at two sides on the surface thereof.
For example, Japanese Unexamined Patent Publication (Kokai) No. Heisei 8-21524 discloses an absorbent article having leakage preventing walls which are prepared from webs deformed into a non-planar shape by machine work. The leakage preventing wall formed from the web functions as an elastic strip exhibiting an elastic contractive force in the longitudinal direction of the absorbent article.
In International Unexamined Patent Publication (Kohyou) No. Heisei 9-503934, on the other hand, there is disclosed an absorbent article formed with elastic pleats at two sides in the width direction thereof. The elastic pleat portion has a surface to face the skin so that the elastic pleats are in contact with the skin upon wearing. The elastic pleat portion entirely has a Z-shaped cross section.
As described in the foregoing, the conventional absorbent articles have a leakage preventing wall formed from a web deformed into a non-planar shape or formed with elastic pleats.
However, the conventional leakage preventing wall itself functions as an elastic body for upstanding from the surface of the absorbent article or for incurvating the absorbent article. Therefore, it has such a defect that a body fluid is liable to be retained in a concave part of an irregular shape (i.e., the non-planar shape or the pleat shape), and contamination due to the body fluid is liable to remain on the leakage preventing wall itself.
In the absorbent article disclosed in Japanese Unexamined Patent Publication (Kokai) No. Heisei 8-21524, moreover, since the leakage preventing wall formed from the non-planar web upstands perpendicularly on the surface, the leakage preventing wall is liable to fall down when the leakage preventing wall is in contact with the skin of the wearer. If the leakage preventing wall falls down toward the center of the surface at this time, a part of the absorption region on the surface is covered with the leakage preventing wall to reduce the substantial liquid absorbent area, whereby the entire liquid absorbing performance is lowered.
In the absorbent article disclosed in International Unexamined Patent Publication (Kohyou) No. Heisei 9-503934, on the other hand, since the elastic pleats are arranged in substantially parallel to the surface of the absorbent article, it has such a problem that a body fluid attached to the concave part of the elastic pleat portion is difficult to flow down toward the surface of the absorbent article, whereby the body fluid is liable to remain in the concave part.
Furthermore, because both the leakage preventing walls are formed to have an elastic force by themselves, the leakage preventing walls per se have a low rigidity. Accordingly, when they are provided to upstand from the surface of the absorbent article, for example, the buckling strength of the leakage preventing wall cannot be so high. Therefore, when a leakage preventing wall having a steric shape is formed, it is difficult to maintain the steric shape.
An object of the invention is to provide an absorbent article having a leakage preventing wall which is difficult to fall down on a liquid absorption region on contacting with the skin of the wearer, so as not to decrease the absorbent area on the surface of the absorbent article.
Another object of the invention is to provide an absorbent article having a leakage preventing wall which prevents a body fluid attached thereto from being retained in a concave part of an irregular shape of the leakage preventing wall.
A further object of the invention is to provide an absorbent article having a leakage preventing wall of a high rigidity and a high buckling strength, which is difficult to fall down due to a pressure caused by contact with the skin, whereby the steric shape of the leakage preventing wall can be maintained.
According to one aspect of the invention, there is provided an absorbent article comprising:
a body portion including a liquid permeable front surface sheet for facing the wearer, a back surface sheet, and an absorbent layer sandwiched between the front surface sheet and the back surface sheet; and
leakage preventing walls extending in a longitudinal direction of the body portion and arranged at two sides thereof in a width direction perpendicular to the longitudinal direction,
the leakage preventing wall including a side wall part upstanding from the surface of the body portion and a skin contacting part extending from the upper end of the side wall part toward the outside of the body portion in the width direction, a fold inducing part being formed to extend in the longitudinal direction at a middle part between the upper end and the lower end of the side wall part, whereby the side wall part is folded with the fold inducing part moved toward the outside of the body portion in the width direction when the skin contacting part is pressed toward the surface of the body portion.
Preferably, both ends in the longitudinal direction of the leakage preventing wall are fixed on the surface of the body portion in such a state that the side wall part is folded with the fold inducing part moved toward the outside of the body portion in the width direction and the skin contacting part is superposed on the folded side wall part.
With the fold inducing part being provided, the leakage preventing walls are folded compactly at two sides on the surface of the body portion when the skin contacting part is brought into contact with the skin of the wearer and pressed toward the surface of the body portion, whereby the leakage preventing wall is difficult to fall down toward the center on the surface. As a result, the liquid absorbent area on the surface of the body portion is not substantially decreased. Furthermore, when both the ends in the longitudinal direction of the leakage preventing wall are fixed in such a folded state on the surface of the body portion, the absorbent article is incruvated in the longitudinal direction, and thus the leakage preventing wall can easily upstand in the middle position between two end edges of the absorbent article.
For easy upstanding of the leakage preventing wall, preferably, elastic members exhibiting a contractive force in the longitudinal direction are attached to the fold inducing part and the skin contacting part.
Preferably, the leakage preventing wall comprises nonwoven fabric formed to have a wavy form, of which top parts and bottom parts are alternately arranged in the longitudinal direction and extend perpendicular to the longitudinal direction.
When the leakage preventing wall is formed with the nonwoven fabric thus shaped, the buckling strength of the side wall part is increased, and the leakage preventing wall is difficult to fall down by a pressure from the skin toward the surface.
Preferably, the fold inducing part has a density that is different from a density of other parts of the side wall part. Also preferably, at least one of side edges of the skin contacting part has a density that is different from a density of other parts of the leakage preventing wall.
When the density of the fold inducing part is differentiated from the density of the other parts, the leakage preventing wall is easily folded at the fold inducing part. When the density of the side edges of the skin contacting part is differentiated, the skin contacting part is easily folded in such a direction that the skin contacting part fits the skin, and the nonwoven fabric is easily folded into two at the side edge on the free end of the skin contacting part.
According to another aspect of the invention, there is provided an absorbent article comprising:
a body portion including a liquid permeable front surface sheet for facing the wearer, a back surface sheet, and an absorbent layer sandwiched between the front surface sheet and the back surface sheet; and
leakage preventing walls extending in a longitudinal direction of the body portion and arranged at two sides thereof in a width direction perpendicular to the longitudinal direction,
the leakage preventing wall comprising nonwoven fabric formed to have a wavy form, of which top parts and bottom parts are alternately arranged in the longitudinal direction and have a higher density than that of midway parts between the top parts and the bottom parts, and the leakage preventing wall having a slant part slanting to leave from the surface of the body portion toward the outside of the body portion in the width direction.
Preferably, the top parts and the bottom parts of the wavy form have a density of 0.1 g/cm3 or more. The upper limit of the density at the top parts and the bottom parts is preferably about 1.0 g/cm3.
When the density of the top parts and the bottom parts of the wavy form of the nonwoven fabric forming the leakage preventing wall is made higher as above, the buckling strength of the leakage preventing wall can be increased. Moreover, a body fluid attached to the leakage preventing wall can easily flow down the slant part thereof toward the surface of the body portion along the parts having the higher density.
Preferably, the leakage preventing wall has such a structure that the nonwoven fabric is folded into two at a free end of the leakage preventing wall to form an inner gap between two folded portions of the nonwoven fabric.
With the gap being provided, the liquid permeability of the leakage preventing wall can be decreased to improve the leakage preventing effect, and the feeling on contacting with the skin can be softened to improve the wear feeling.
Preferably, an elastic member exhibiting a contractive force in the longitudinal direction is interposed between the two folded portions of the nonwoven fabric, and the elastic member is fixed to the two folded portions of the nonwoven fabric, respectively, at the bottom parts of the wavy form thereof.
Owing to the structure, the leakage preventing wall can have a sufficient contractive force in the longitudinal direction without imparting an excessive elastic contractive force to the elastic member.